It's a little unclear if you have to sign up for it or not. They mention "Battlefield Insider Members" getting early access, but I'm not sure if that means before August 31, or you have to actually be an Insider Member to even play the open beta. I signed up just to be safe.

Beta is up, 7.1gb download, need up to date video drivers, had a quick game, not sure if i like it or not yet, i played as a medic, had a crap rifle, only kills i got were with my pistol. Felt like a sniper with a med pack..... might suit some of you.....